Electrical lamps



Nov. 11, 1958 J; w. T. WRIGHT ET AL 2,860,274

I ELECTRICAL LAMPS Filed July 11, 1956 INVENTOPJ JOHN W/LL 006MB) 7/IOMMS [Vi/6H7 400N940 FIRTHUR 'HOWLEJ Unite States Patent ELECTRICAL LAMPS John Willoughby Thomas Wright and Donald Arthur Howles, Leicester, England, assignors to The British Thomson-Houston Company Limited, London, England, a British company Application July 11, 1956, Serial No. 597,114

Claims priority, application Great Britain July 21, 1955 3 Claims. (Cl. 313-318) This invention relates to electric lamps and more particularly to the smaller or miniature types of incandescent lamp such as those used on automobiles or cycles in which the filaments should occupy a definite position in the bulb. Such lamps are usually made by the buttseal method in which an exhaust tube is sealed to the neck of the bulb and the leading-in wires are sealed through the sides of the neck at the glass joint made between the exhaust tube and the bulb.

After sealing and exhausting operations have been completed the lamps heretofore have been provided with a metal cap which is attached to the neck of a bulb by means of a cement or plaster. This method of manufacture has the disadvantage that owing to the nature of the sealing operation it is difficult to control the location of the filament in the bulb, and even if the filament is positioned correctly loose or faulty capping may result in the axis of the lamp being out of line with the axis of the cap.

As lamps of this type are frequently used with a reflector it is most important that the filament should occupy a definite position with respect to any reflector employed with the lamp and that the base of the lamp should be firmly and securely housed in its holder.

According to our invention we obviate the above disadvantage by providing a lamp which is capless and in which the filament and mount structure are correctly located prior to the sealing operation and held firmly in that position during the time that the exhaust tube is being sealed at the neck of the bulb. v

To this end, our invention consists of an electric lamp, the neck of which is provided with protuberances or projections formed integrally therewith and adapted to engage or fit snugly into an insulated holder suitably adapted to receive the protuberances. Our invention further consists in so disposing the ends of the leading-in wires that prior to their being sealed in the joint made between the exhaust tube and the neck of the bulb, the mount structure carrying the filament is correctly located within the bulb and held in that position by the sealing operation.

The invention may be better understood from the following description read from the accompanying drawing, in which:

Fig. 1 shows the lamp constructed according to the present invention, and

Figs. 2 and 3 show two views of another lamp constructed according to the invention in which the leading-in wires are extended into a pocket formed in the bulb to provide greater stability of the filament.

In the drawing, like references have been given to the corresponding parts of the two lamps illustrated and 1 indicates a bulb which may be of granulated glass if desired. Sealed thereto is an exhaust tube 2, which seal may be either a ring seal, or a butt seal as shown at 3. The leading-in wires 4 are brought through the seal 3 and in our preferred embodiment the ends of the leadingin Wires brought outwardly of the seal are bent into the form of a stirrup 5 to form a portion which extends circumferentially about the outside of the neck of the bulb and re-enter the seal some distance away from the points at which they emerge.

The projections 6, which are formed integrally with the neck of the bulb, are shown as having a rectangular configuration, but may well have any other configuration such as hemispherical, provided that the holder which it is intended to use with the lamp fits snugly round the neck of the bulb so as to retain it firmly in position. It is preferable that the projections 6, or at least one of them, has a straight portion in alignment with the axis of the bulb to keep the lamp in axial alignment with respect to the socket or any reflector associated therewith.

The lamp shown in Fig. 1 and the modified version thereof shown in Figs. 2 and 3 are conventional in respect of the formation of the leading-in wires and] the manner in which the filament is connected across them. Wellknown means, such as a glass bead is employed to keep the leading-in wires mutually stable and in spaced-apart relationship. In the modification shown in Figs. 2 and 3, the leading-in wires are extended so as to rest within a pocket 7 formed in the glass of the bulb 1 to give greater stability to, and more accurate location of, the filament.

As is well-known in the art the wire from which the lead wires are formed is made compatible with the glass which comprises the bulb and exhaust tube, that is to say their relative coelficients of thermal expansion are matched to a considerable degree.

While for most practical purposes two projections formed on the neck of the bulb will be sufiicient it is not intended that the invention should be limited to two only.

It will be seen from the foregoing description that considerable advantage obtains from our invention in that lamps made in accordance therewith are capless and in addition to the advantages already mentioned above, have the great advantage that in manufacture, such lamps can be made on a single machine, the necessity for the additional step of capping the lamps which usually involves taking it from one machine to another which carried out that step, being redundant. Furthermore the leadingwires are each firmly anchored into the glass of the neck at two points and constitute direct communication to the supply of the lamp whereby faults due to broken wires, dry soldered joints etc. are eliminated.

What we claim is:

1. An electric lamp comprising a bulb having a neck portion, an exhaust tube, a seal of said exhaust tube to said neck portion in end-to-end relationship therewith, a filament, a filament mount structure locating said filament within said bulb and including filament lead wires which emerge through said seal between said exhaust tube and said neck portion and re-enter said seal at points distant from the points of emergence of said lead wires, and the portions of said lead wires remote from said filament being formed as contact stirrups embracing parts of said neck portion away from said seal and accurately locating said filament in place within said bulb prior to the formation of said seal.

2. An electric lamp comprising a bulb having a neck portion, an exhaust tube, a seal of said exhaust tube to said neck portion in end-to-end relationship therewith, a filament, a filament mount structure locating said filament within said bulb and including filament lead wires which emerge through said seal between said exhaust tube and said neck portion and re-enter said seal at points distant from the points of emergence of said lead wires, the portions of said lead wires remote from said filament being formed as contact stirrups embracing external parts of said neck portion away from said seal and accurately locating said filament in place within said bulb prior to the formation of said seal, and a plurality of protuberances distributed around said neck portion away from said contact stirrups and engageable with parts of a suitable. lamp holder for correctly locating. said lamp within thelatter.

3; An electric lamp comprising a bulbhaving a neck portion, an exhaust tube, a seal of .saidlexh aust tubeto said neck portion 1 in end-to-end T relationship therewith,

a filament located Within said bulb andflead wires.con-' seal, and a plurality of protubcrances distributed around said neck portion away from said contact stirrups and" engageable with parts of a suitable lamp holder for correctly locating said lamp within the latter.

References Cited in the file of this patent UNITED STATES PATENTS 244,277 Maxim July 12, 1881 268,270 Nichols Nov. 28, 1882 383,675 Thompson May 29, 1888 488,636 Prentiss Dec. 27, 1892 1,893,305 Rentschler Jan. 3, 1933 1,983,362 Geiger et a1. Dec. 4, 1934 2,359,483 Kuebler Oct. 3, 1944 2,542,326 Greiner Feb. 20, 1951 

